In the manufacture of products, such as industrial and automotive components, various small parts, such as stampings, castings, seat and clamp assemblies, bolts, clamps, conduit, pipes, and the like, are employed that mainly serve a functional role in the final assembly. In order to prepare these parts for final assembly, a coating material is typically deposited on at least portions of the part. In many instances, the entire part is coated to provide a finished appearance to the part and/or provide protection to the underlying substrate from damaging effects as a result of use, wear, and/or environmental conditions.
Because of the substantial number of small parts employed in the manufacturing industry, various coating techniques have been employed for depositing material on these parts at high speeds. For example, small parts can be spread and loosely placed on a flat metal mesh conveyor belt for high-speed coating. The parts are transferred to one or more additional belts prior to the parts being processed through a drying unit. In many instances, the individual parts come in close proximity to or engage each other while passing through the coating and drying systems such that when the coating is applied over the parts and dried or cured, two or more parts may adhere together at the point of engagement (known as a “touch point”). These coated parts must then be separated from each other with some degree of force that, typically, results in the removal of at least some of the coating from each of the parts at or around the touch point. Touch points may also be formed when a part touches the side of the conveyor. Additionally, even if no contact is made between parts or the sides of the conveyor, contact is still present between the part and the conveyor belt that it is resting on, and a touch point is present at each point of contact with the belt. This is particularly the case in electrophoretic coating processes that require the conveyor belt to be in electrical contact with the part to supply the necessary charge prior to or at the time of coating.
At the very least, the touch point provides an unsightly blemish on the finished product. When the part is formed from a corrosive material, the touch point, in addition to its reduced appearance, has a substantially greater chance of developing premature signs of corrosion following assembly. Because the parts are randomly positioned on the belt, it is difficult to predict the location of the touch points prior to coating.
In the coating process described above, because, for example, the small parts are randomly placed on the conveyer belt and the parts are transferred to one or more additional belts prior to the drying unit, it has been difficult to minimize the occurrence of touch points. Accordingly, in order to meet quality standards, the supplier employing this coating technique may find it necessary to incur time and cost consuming efforts to sort and scrap non-conforming parts.
Coating processes that can materially reduce or avoid the shortcomings discussed above and/or improve coating and manufacturing efficiency, while providing a coated part that meets or exceeds functional and aesthetic quality requirements, are desired.